Process of treating castings



HT rrf ALLEN :B, NORTON, or; CLEVELAND, onro, ASSIGNOR mo rm ALUMINUM. css'rmes COMPANY, or CLEVELAND, omo, A. conronn'rron or 0310.

rnocnss or TREATING cesrmes.

Specification of Iretters Patent.

Patented July 5-, 1921.

No Drawing. Application filed August 5, 1918, Serial No. 248,277. Renewed April 11, 1921. Serial To all whom it may concern Be it known that I, ALLEN B.'NoR'ro N, a citizen of the United States, residing at Cleveland, in the county of Cuyahoga and State of Ohio, have invented a certain new and useful Process of Treating Castings,- of which the following is a specification;

This invention relates to an improved process of treating porous castings for the purpose of rendering them impervious to fluids and especially to liquids. While, in certain of its broader aspects, the invention is not limited to the treatment of castings'of any particular material, it has been devised especially for the treatment of castings made of aluminum or aluminum alloys.

provision of a process of treating porous I ing are stopped with material insoluble inv One of the objects of the invention is the provision of a process of treating porous castings to render them leak proof, by which process reagents are caused to enter the pores of the casting and therein to bring about a chemical reaction with'the resultant formation of a compound having suflicient bulk to stop the pores.

Another object of the invention is the castings to render them leak proof by subjecting the constituent material of the castings to the action of a reagent capable of penetrating the pores of the said material and re-acting chemically therewith to form in the pores a compound having sufiicient bulk to effectively stop the pores.

Another object of the invention is the provision of a process of the character last referred to in which the pores of the castwater, and preferabl also in oil.

Another. object o the invention is the provision of a process of the character in question especially adapted for the treatment of porous castings made of aluminum or aluminum alloys.

A further object of the invention is the provision of a process of the character in question which is capable of being carried out in a simple and effective manner and at a very moderate cost.

In the use of castings which serve as containers or retainers of fluids it has been found difiicult in many cases to secure cast- -ingswhich would not prevent more or less rendering. the castings more or less pervious to flu ds; and since such castings are very extenslvel used under condltlons calling for leak-proo qualities, it has been a pressing problem-to devise some method of saving the substantial percentage of castings whichv would otherwise be rejected on account of porosity that would in no wise diminish the utility of the casting for purely structural purposes. 'For example, aluminum (or, more strictly speaking aluminum alloy) castings are now extensively used in the production of internal combustion engines, the crank case and manifolds commonly being -made of aluminum and, in numerous cases, the cylinder block and even the cylinder head are also cast of this material. Also transmission gear cases and oil and water pump parts used in connection with such engines are usually made of aluminum. In the case of each of these castings, porosity, especially porosity marked enough to permit the passage of liquids, destroys the usefulness of the casting. Thus the crank case must not permit leakage of the lubricating oil with which it is interiorly flooded; the

der and cylinder head castings must be impervious to the jacket water. Obviously the gear cases and oil pumps must be impervious to oil and'the water pum s to water.

Heretofore, as far as am aware, there has been no satisfactory method of treating aluminum casti to overcome these difiiculties, and this l iiave sought to accomplish by my present invention.

In the treatment of aluminum castings such as have been referred to by my improved process I provide in a suitable container, e. g. a steel or iron tank, a more or less concentrated aqueous solution of sodium acetate to whichlis added ammonium chlorid. A satisfactory solution, for example,

-- treatmentwould continue for eight hours or so in case of slight porosity, up to. sixteen. or even twenty-four hours yvghere the poms-- in the hotsolution, the'castings are removed ity is greater,

wou 'd consist of 100 pounds commercial sodium acetate and 50'pounds 'of ammonium chlorid dissolved in water to bring the total volume up to 38 cubic feet; In this solution I immerse the casting .or as much thereof as is to be treated-,-ordinarily the casting is immersed bodilyand the solution isconcentration ofthe solution and the degree orosity of the casting. With a solu-' of the tion of .the strength above indicated, the

- 0 v v 7 Following this treatment of the castings and allowed to thoroughly drain. This completesthe essential steps of the recess and the'castings can next be tested or leaks in any suitable manner. Ordinarily, however,

' I prefer, before testing the treated castings to place them in an .'oven and subject them to a temperature preferably somewhat above 2129 F. until the castings are thoroughly dried out..

."I have not determined the precise chemiout of this process which I have describe cal reactions that take lace in-the carrying but the sodium acetate solutio n, penetrating the pores'of the casting, either directly orwith intermedlate reactions attacks the aluminum with the ultimateformation-of alunnnum acetate and the heating, more or less prolonged, results in the transformation of r the aluminum acetate to aluminum hydroxid and acetic acid. The insoluble aluminum 'hydroxid thus formed has substantially greater bulk than the aluminum entering I into the combination to forni the hydroxid and consequently the latter, formed in situ' in the pores ofthe casting, serves effectively to stop the pores and render the casting or baking of the castings after treatment in: ,the boiling 50111131011, when such drying or correspondingly impervious to passage of fluids. It is quite probable that the drying baking is parried out,- may act" to convert some of'the aluminum hydroxid to aluminum oxid in addition to driving off fre'e moisture.

In either case,'the treatment results in the stoppmg of the ores as above set forth.

I have not re erred to the action'of the ammoniumchlorid, and I am not at'present .able to explain its action. However, I be lieve that itas'sists the reaction between the sodium acetate and the aluminum because the chlorids more readily attack aluminum than do the acetates. It seems robable that the'chlorid assists in getting t e aluminum ion into' solution and :thus facilitates the reaction between the aluminum and the acetate. A

As will readily be understood, the actionof the solution on the metal of the castings will be more or less marked according to the strength ofthe solution, the temperature of 'the.,solution,"and tl1e length of the treatment. Thus by using a more concentratedsolution than that above specified, viz.,.2() pounds of sodium acetate and 10 pounds of I have secured good results from a treatment of eight hours even where the porosity of' the castings 'was. marked. The application of heat to the solution 'during the treatment of the castings especially serves to-hasten ammonium chlorid per cubic foot oflwater,

the reaction of the acetate .and the aluminum. It is to be observed also, that the heating of the solution and therefore of the castings tends toexpand the pores in"'thc latter and-to drive off occluded air so that i the solution more readily enters the pores of.

the metal. If it is desired to do so, the treatment can bev carried out in hermeticaliy tight chambers from which the air can be ex-' hausted and which can be. subjected to' greater than atmospheric pressure, for "the purposes, respectively, of facilitating the removal of air occluded in the pores of the solution into the pores. Suchuses of vacuum and pressure are well understood in connection with impregnation ,treatments and need not be described in detail..

' With respect to the use of vacuum and casting, and subsequently introducing the I pressure, I may state that I have been able to secure satisfactory results without .re-

course to either vacuum or pressure and accordlngly the apparatus. necessary for carryingout the process and the process itself are simple, readily understood and mastered by .the average workman. Obviously the appar atus' is ca able of bein. cheaplyproduced and maintained and t e process lends itself to treatment of castings 1n quantities.

Obviously the substance formed in. the

pores in the presence of the aqueous solu-. tion must be insoluble in water; it is also insoluble in oils; Consequently the process iswell adapted for the treatment of internal combustion engine castings such as have i been mentioned above.

' While I prefer to subject the castings to i theaction of a reagent in aqueous solution, as-has been set forth, it will of course, be understood that the invention is not limited to the use of a re gent in liquid form. For example, the cas mgs might be introduced into a closed chamber and subjected to the action of a reagent in vapor form, the vapor' penetrating the pores of the casting and reacting with the metal thereof to form in the. I pores substance of sufiicient bulk to stop the poresas set f r h in connection with he use 18 other known way.

Other ways of applying or carrying out the invention will occur to those skilled in articles which includes subjecting the article such matters.

I WhatI claim is: a I 1. A- process of treating porous metallic to the action of fluid reagents in a manner to cause the latter to enter the pores of the article,- forming by chemical reaction within the said pores a solid compound having suflicient bulk to stop the said pores and heating the article to changethe nature of the solid compound.

2. .A process of treating porous castings'. which includes subjecting the casting to the action of a reagentin a manner to cause the latter to enter the pores of the casting and therein form with the constituent material of the casting a solid compound having sufiicient bulk to stop the said pores.

3. A process of treating porous castings which includes subjecting the casting to the action of a fluid in a manner to cause thelatter to enter the pores of the casting and therein "form with the constituent material of the casting a solid compound having suflicientbulk to stop the said pores- .4. A process oftreating porouscastings 5. A process-of treating porous castings which includes immersing the casting ina chemical solution adapted to enter theipores of the casting and therein form with the constituent material of the casting a solid compound having sufiicient vbulk to stop said pores, and heatingthe solution and casting sify the chemical action of the solution'onthe casting.

6. A process of treating porous castingsto expand the pores of the latter, drive out from said pores occludedair and cause entrance therein of the solution and to intenwhich includes immersing the casting In a chemical solution adapted to enter'the pores of the casting and therein form with the constituent material of the castinga solid compound having sufiicient bulk to stop said pores, heating the;:solution and casting to expand the pores of the latter, drive out from said pores occluded air and cause entrance therein of the solution and to intensify the reaction of the chemical solution ing to .the action of a reagent including an acetate in a manner to cause said reagent to enter the pores of the casting and therein formwlth the aluminum a solid compound havin suflicient bulkto stop the said pores.

8. process of treating porous aluminum castings which consists in immersing the casting in an alkali acetate solution in a manner to cause said solution to enter the pores of the casting and therein form with the aluminum a solid compound having sufficient bulk to stop the said pores.

9. A process of treating porous aluminum castings which includes immersing the casting in a solution of sodium acetate and ammonium chlorid in avmanner to cause said solution to enter the pores of the casting andt'herein form with the aluminum a solid compound having suflicient bulk to stop the said pores. w, I

10. A process of treating porous aluminum castings which includes immersing the casting in a hot solution of sodium acetate and ammonium chlorid.

11. A process of treat-mg porous alumlnum cast ngs which mcludes immerslng the casting 1n a hot solution of sodium ace- 7 tate and ammonium chlorid-and heating the casting, after its removal from the solution, to drive oil water.

12. A process of treating porous aluminum castings which "includes subjecting the casting to the action of a boiling solution of sodium acetateand ammonium chlorid.

-13. A process of treating porous aluminu'm castings whichconsists in subjecting the casting to the action of a reagent including an acetate in a. manner to "cause said re-.

agent to enter the pores of the casting and f therein form with the aluminum a solid compound having sufficient bulk to stop the said pores, and intensifying the reaction of the acetate and aluminum by the applica- 'tion of heat orotherwise.

1A. A process of treating porous aluminum castings which consists in subjecting and-intensifying the reaction of the vacetate and aluminum by the application of heat or otherwise.

*15." A process of treating porous alu- 'minum castingswhich consists in subjecting the castings to the action of a reagent ineluding an alkali acetate and a halogen com pound in a manner to cause said reagent to enter the pores of the casting. and therein form. with the'elnminum 41 solid compound j having suflicie'nt'bulk to stop the said pores.

16; A process of treating porous aliiminum castings which includes immersing the casting ina solution of an-alkali acetate and a halo en compound in a manner to cause said solutlon to enter the pores of the casting and therein formwith the aluminum a,

signature. K l ALLEN B NORTON,

' su'flicient hn lk to I10 cle of mannfacture' an 

